Vacuum coating apparatus having means for positioning one of a plurality of members at a selected location between the substrate and the coating material source

ABSTRACT

A vacuum coating apparatus of the gaseous discharge sputtering type is described. Such apparatus includes a target electrode, means for initiating and sustaining a gaseous discharge for sputtering coating material from a holder for supporting a substrate in the line-of-sight of the target for receiving coating material sputtered therefrom. Mechanisms are included for positioning any one of a plurality of coating masks over the substrate to provide a desired coating pattern, and for positioning any one of a plurality of sputter targets at the target electrode to obtain sputtering of, and consequent coating by, different materials. Actuation mechanism extends to the exterior of the vacuum chamber housing the sputtering apparatus for actuating both the mask moving and target moving mechanisms from the exterior of the chamber.

May 9, 1972 w, BRUCE EI'AL 3,661,759

VACUUM COATING APPARATUS HAVING MEANS FOR POSITIONING ONE OF A PLURALITY OF MEMBERS AT A SELECTED LOCATION BETWEEN THE SUBSTRATE AND THE COATING MATERIAL SOURCE Filed Feb. 19, 1970 3 Sheets-Sheet INVENTORS N HAROU) WILLIAM BRUCE WERNER E. SANDVOSS BY 8, FW

ATTORNEY FIG. I

May 9, 1972 w, BRUCE ETAL 3,661,759

VACUUM (JOAFING APPARATUS HAVING MEANS FOR POSITIONING 0M3 OF A PLURALITY OF MEMBERS AT A SELECTED LOCATION BETWEEN THE SUBSTRATE AND THE COATING MATERIAL SOURCE Filed Feb. 1.9, 1970 .5 Sheets-Sheet 2 FIG. 2

May 9, 1972 H, w, BRUCE EI'AL 3,661,759

VMJUIJM UUA'I'ING APPARATUS HAVING MEANS FOR POSITIONING mm 01" A L'LURALITY OF MEMBERS AT A SELECTLD LOCATION BETWEEN THE SUBSTRATE AND THE COATING MATERIAL SOURCE Filed Feb. 19, 1970 3 Sheets-Sheet 3 FIG. 3

FlG.6n

24 2 24 FIG. 4b FlG.5b FIG.6b INVENTORS HAROLD WILLIAM BRUCE WERNER E. SANDVOSS ATTORNEY 3,661,759 VACUUM COATING APPARATUS HAVING MEANS FOR POSITIONING ONE OF A PLURALITY OF MEMBERS AT A SELECTED LOCATION BE- TWEEN THE SUBSTRATE AND THE COATING MATERIAL SOURCE HaroldWilliam Bruce, PaloAlto, and Werner E. Sandvoss, San Jose, Calif., assignors to Varian Associates, Palo Alto, Calif. I

Filed Feb. 19, 1970, Ser. No. 12,561 Int. Cl. C23c 15/00 US. Cl. 204-298 12 Claims ABSTRACT OF THE DISCLOSURE A vacuum coating apparatus of the gaseous discharge sputtering type is described. Such apparatus includes a target electrode, means for initiating and sustaining a gaseous discharge for sputtering coating material from a target positioned at the target electrode, and a substrate holder for supporting a substrate in the line-of-sight of the target for receiving coating material sputtered therefrom. Mechanisms are included for positioning any one of a plurality of coating masks over the substrate to provide a desired coating pattern, and for positioning any one of a plurality of sputter targets at the target electrode to obtain sputtering of, and consequent coating by, different materials. Actuation mechanism extends to the exterior of the vacuum chamber housing the sputtering apparatus for actuating both the mask moving and target moving mechanisms from the exterior of the chamber.

DISCLOSURE Background of the invention The present invention relates to vacuum coating apparatus and, more particularly, to a mechanism for such an apparatus capable of positioning any selected one of a plurality of members at a preselected location between a substrate to be coated by deposition and the means for providing at the substrate an atmosphere of the coating material for the deposition.

Most microelectronic components now in use are produced by the application onto a substrate of a plurality of thin layers of conductive or semiconductive material. Vacuum coating apparatuses, such as those of the gaseous discharge sputtering type, are the only coating apparatuses now available capable of providing the necessary thin films of material. Such apparatuses generally include means of one sort or another for providing at the substrate surface to be coated an atmosphere of the desired coating material. The material then deposits from the atmosphere onto the substrate. It will be appreciated that in order to prevent contamination and produce the atmosphere, the coating procedure must be undertaken under controlled vacuum conditions such as within a vacuum chamber. The necessity of such vacuum conditions has raised problems with respect to the efficiency of the coating operation, as well as the quality of the coatings obtained. That is, most microelectronic components require the application of several different layers of different materials on the substrate, with each layer being in a different geometrical pattern on the substrate than the others. Thus, between the application of any layer and subsequent layers, certain manipulative steps must be made. For example, the source of the first coating material must be replaced with a source of the subsequent coating material, and a mask positioned over the substrate to assure that the subsequently applied material will only deposit at the desired locations on such substrate. In many apparatuses now available, it is necessary to open the vacuum chamber in order to effect the necessary changes. This is especially true with respect to the positioning of masks on the substrate since such masks must be precisely aligned on the substrate to assure the proper interrelationship of the various layers of material. The necessity of opening the vacuum chamber creates a significant delay in the process sincethe chamber must be brought up to atmospheric pressure before opening and then again pumped down before the coating operation can be resumed. Moreover, the subjection of a coated substrate surface to normal atmospheric conditions will often result in contamination thereof by atmospheric gases with consequent deleterious effects to the electrical characteristics of the coating. Some coating materials used in producing microcircuitry components are reactive with gases commonly found in the atmosphere and, therefore, subjection of the same to normal atmospheric conditions will destroy the integrity of the material.

Vacuum coating apparatuses have been made available in the past which do not require that the vacuum chamber be brought up to atmospheric pressure between the coating of a substrate with different layers of material. The designers of most such systems, however, have generally taken the direction of providing in one vacuum chamber several different sets of the major elements used in a coating operation. For example, in order to provide the capability of sequentially coating a substrate with layers of different materials, some apparatuses include separate coating stations, with the necessary equipment therefor, for each material Besides this redundancy of equipment being costly, it requires complicated mechanisms for moving either the substrate to be coated or the work stations to the proper position for the sequential coating. While some apparatuses are available which do not require separate work stations to provide the different coatings, the complexity of the mechanisms enabling this generally limits the same to permitting only two or three different materials to be sequentially applied to a substrate.

SUMMARY OF THE INVENTION The present invention provides a simple mechanism by which any selected one of a plurality of members, such as any one of a plurality of substrate masks or sputter targets, may be precisely positioned at a selected location within a vacuum chamber between a substrate supporting means and a coating element. The apparatus therefore enables sputtering from any one of a plurality of targets with only one target electrode, as well as the provision of selected different masks at the substrate, without the necessity of entering the vacuum chamber. In its basic aspects, the invention includes means for supporting locations within the vacuum chamber removed from the substrate coating element, the plurality of members it is desired to position, as well as two means for moving each of the members. One of the moving means is adapted to move each of the members to a position between the substrate and the coating element, and the other is adapted for moving each of the members in the direction of the line-of-sight between the substrate and the coating element. The invention also includes means extending to the exterior of the vacuum chamber for actuating the two moving means Within the chamber. By in turn moving a selected one of the members in the two directions noted, the member can be brought to the desired preselected location between the substrate and coating element from the exterior of the chamber. The two moving means are so designed that each is capable of moving any one of the members to the preselected location. Thus, the necessary mechanism for providing the different members at the precise location is reduced to a minimum.

3 BRIEF DESCRIPTION OF THE DRAWINGS With reference to the accompanying three sheets of drawings:

FIG. 1 is a partial, broken-away side elevational view of a vacuum coating apparatus incorporating a preferred embodiment of the invention;

FIG. 2 is a cross-sectional view of the apparatus illustrated in FIG. 1 taken on a plane indicated by the line 22 in FIG. 1;

FIG. 3 is a partial sectional view of the apparatus of FIG. 1 taken on a plane indicated by the lines 33 in FIG. 1; and

FIGS. 4A-6B are schematic illustrations of the movement provided by the mechanism of the instant invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT With reference to FIGS. 1 through 3 of the accompanying drawing, a vacuum coating apparatus is generally referred to by the reference numeral 11. Apparatus 11 is of the gaseous discharge sputtering type. That is, the desired atmosphere of coating material is provided at the substrate surface by bombarding a target of the selected coating material with high energy positive ions to effect removal of particles of the coating material from the target for deposition onto, and adherence to, the substrate. In accordance with conventional practice, apparatus 11 includes a vacuum chamber 12 mounted on a base 13 which, in turn, has a vacuum system 14 in communication therewith.

Means are provided within chamber 12 for producing a gaseous discharge to effect the ion bombardment and to cause deposition of the resulting particles of the coating material onto a substrate. More particularly, a hollow support post 16 extends vertically upward within chamber 12 and has secured thereto intermediate its ends by a bracket .17 a conventional target electrode 18. Either a negative D.C. or radiofrequency bias can be suitably applied to electrode 18, such as by means of an electrical lead 19 which passes to the exterior ofthe vacuum chamber. Lead 19 can be in the form of a hollow conduit for passing a suitable cooling fluid to the target electrode in order to control its temperature as desired.

Means are also provided for supporting a substrate to be coated at a position spaced from the target electrode but in the line-of-sight thereof. For this purpose, a substrate holding plate 21 is suspended over target electrode 18 by an L-shaped angle arm 22. As is illustrated in FIG. 1, leg 23 of arm 22 is pivotally mounted on a shaft 24, and actuation linkage 26 secured to such arm is, in turn, pivotally mounted on an upper plate 27 of a support frame which is generally referred to by the reference numeral 28. An actuating lever 29 is secured to linkage 26 through plate 27 and includes a set screw 31 for setting the position thereof with respect to plate 27. It will me appreciated that this arrangement, in accordance with conventional mechanics, is usable to selectively pivot substrate holder 21 about the axis of rod 24 to a location removed from the other structure of the coating apparatus to facilitate interchanging substrates held thereby.

The apparatus also includes means for selectively heating or cooling the substrate. For this purpose, a combined heater and cooling assembly 32 is suspended in close proximity over the normal location for substrate holder 21. Such assembly includes a water cooled table 33 to which is removably secured a light reflector 34 in which heater lamps, such as quartz, iodide lamps 35, are located. Light reflector 34 as shown is available from Research, Incorporated, Minneapolis, Minn. as Model No. AUS- 609. Whenever it is desired to cool a substrate instead of heat the same, the reflector 34 and its associated lamps may be removed from the structure, and the table 33 brought into close proximity with the substrate. Passage of coolant through the table will result in cooling of the substrate by radiation. Assembly 32 is supported on post 16 by a bracket 36. Post 16 includes in its interior the necessary coolant feed tubes and electrical leads for the operation of the assembly 32, and bracket 36 is selectively axially slidable on post 16 to permit the table 33 to be brought into close proximity with the substrate.

Means are provided for initiating and sustaining a gaseous discharge between target electrode 18 and substrate holder 21. More particularly, a two-turn R.F. conducting coil 37 is positioned axially between target electrode 18 and substrate holder 21 for the generation and shaping of an R.F. field to sustain therebetween a. gaseous discharge plasma. An R.F. power supply is suitably connected between the two turns of the coil in a conventional manner, and the coil is in the form of a tube to permit a cooling fluid to pass therethrough. A support post 40 for the coil 37 also carries the necessary electrical leads and cooling fluid tubes for the coil.

As a particularly salient feature of the instant invention, it includes means for positioning a selected one of a plurality of members at a preselected location between substrate holder 21 and target electrode 18. In the instant embodiment, apparatus is provided for positioning chosen ones of two different sets of such members at selected locations. That is, any one of a plurality of mask holders may be precisely aligned with substrate holder 21 to position different masks over the substrate, and any one of a plurality of targets can be positioned adjacent target electrode 18 to have material sputtered therefrom. Such apparatus is supported within the vacuum chamber by the support frame 28 which, in turn, is mounted on a plate 38. Plate 38 is in the form of a discular section and is suitably secured, such as by welding, to the upper edge of vacuum chamber base 13. Support frame 28 comprises a. base plate 39 from which four corner rods 41 extend upward to support upper plate 27 The rod 24 on which the substrate holder 21 is pivoted extends between disk plate 39 and upper plate 27 of the support frame 28 and also acts as means for supporting the plurality of mask holders and a plurality of sputter targets. Although any practical number of mask holders could be used, five are illustrated and are designated with the reference numerals 42, 43, 44, 46 and 47, respectively. The mask holders are mounted for movement together axially of rod 24. That is, such mask holders are pivotally mounted in equal spaced relationship on a linear bearing sleeve 48 which is slidable on rod 24. A collar 49 rigidly secured to post 24 has a pin 50 which extends upward therefrom and is slidably engaged within a corresponding bore in the linear hearing. The collar 49 and its pin 51 prevent rotation of linear bearing 48 relative to post 24 while allowing axial movement between the two members.

Means are provided for axially moving linear bearing sleeve 48 and, hence, mask holders 42-47 along rod 24. For this purpose a rack and pinion drive arrangement, generally referred to by the reference numeral 51, is connected to linear sleeve 48 by a connecting rod 52 (FIGS. 2 and 3). That is, a rack 53 secured to the lower end of connecting rod 52 is engaged by a pinion 54. Pinion 54 is positioned between a pair of elongated bearing support plate 39. A guide support assembly 57 also extends downplate 39. A guide support assembly 57 also extends downward from main plate 38 and supports a roller 58 against the rear side of rack 53 to maintain it in engagement with pinion 54. Pinion 54 is actuated by drive shaft 59 which is coupled through a universal 61 and a mechanical vacuum feedthrough 62 to an operating knob 63.

Means are also provided for pivoting each of the mask holders independently of the other mask holders to a position between the substrate holder 21 and target electrode 18. In this connection, as is best illustrated in FIG. 2, each of the mask holders has an outwardly projecting tongue 66 having an open ended slot 67 for engagement with the moving mechanism. The moving mechanism includes a rod 68 which is supported for axial rotation by a bearing cylinder 69 mounted in base plate 39. The upper end of rod 68 is generally adjacent the location of the tongues 66 of the mask holders and terminates in an outwardly projecting lever 71 which has at its free end a downwardly extending pin catch 72 for engagement within the respective slots 67 of the tongues 66. With this arrangement, whenever the catch 72 is properly aligned with the slot67 in a tongue 66 associated with one of the mask holders, axial rotation of rod 68 and the consequent pivoting of lever 71 will result in the catch engaging with the slot and causing pivotal movement of the mask holder about its support rod 24. The tongue and pivoting mechanism is arranged such that this pivotal movement arcuate- 1y moves each of the mask holders from the position in which mask holder 43 is depicted to that between the substrate holder and the target electrode in which mask holder 42 is depicted (FIG. 2), and vice versa.

Means are provided for actuating rotation of rod 68 from the exterior of chamber 12. That is, a drive shaft 73 is coupled to rod 68 by a pair of bevel gears 74 and passes to the exterior of chamber 12 through a mechanical feedthrough 76. An actuation knob 77 on the end of shaft 73 which is outside of the chamber enables rotation of such shaft and consequent rotation of rod 68.

For ease in understanding how the moving mechanisms of the invention provide the desired positioning of each of the substrate holders, reference is made to FIGS. 4A- 6B which schematically illustrate the movement. Let us assume that it is desired to position mask hoder 43 against substrate holder 21. As is illustrated in FIGS. 4A and 4B, with lever 71 rotated to a position in which catch 72 is free of the substrate holders, the linear bearing sleeve 48 is moved upward with the rack and pinion drive 51 to a position at which upon rotation of lever 71, the catch 72 is engagable with the slot 67 in the tongue 66 of holder 43. Then rod 68 is actuated to rotate lever 71 counterclockwise to engage catch 72 within the slot 67 and cause rotation of mask holder 43 to a location between the substrate holder 21 and the target electrode 18. Iever 72 is continued in its rotation counterclockwise to a position at which the catch is free of the slot 67 and will again not hinder axial movement of sleeve 48. Sleeve 48 is then moved upward to position the mask holder 43 against the substrate holder 21 This movement and positioning is illustrated in FIGS. 6A and 63.

It will be appreciated that to disengage mask holder 43 from the substrate holder 21 and replace it with another one of the mask holders, such as mask holder 44, the steps set forth above are reversed to move the mask holder 43 out of position. Then the mask holder 44 can be moved in the manner described with respect to holder 43 in order to take its place. It will thus be appreciated that a relatively simple mechanism which is earily manipulated has been provided for positioning any selected one of a plurality of mask holders at the desired location against the substrate holder 21.

The invention also includes means for precisely aligning each of the mask holders with the' substrate holder. Thus, upon proper positioning of a substrate in the substrate holder and each mask in the mask holders, one is assured that each mask will be in proper registry with the substrate. The indexing is simply provided by including a socket 81 in the underneath surface of the substrate holder and a complementary pin 82 on each of the mask holders. Due to the common pivoting of the substrate 21 and each of the mask holders on rod 24, engagement of the pin 82 on any one of the mask holders with the socket 81 will provide the desired alignment. The tolerance between the socket and each of the pins is minimized to prevent play and assure precision in the alignment.

As has been mentioned before, the apparatus of the invention also includes means for positioning any one of a plurality of sputter targets adjacent the target electrode for sputtering. Thus, different materials may be sequentially sputtered by the apparatus with th provision of only the one target electrode. The mechanism for providing the target positioning is basically the same as that described above for positioning the mask holders. That is, the plurality of sputter targets, in this instance two denoted by the reference numerals 86 and 87, are mounted for independent pivotal movement with respect to rod 24 by a linear bearing sleeve 88. Sleeve 88 is axially reciprocal on rod 24 by a rack and pinion arrangement 89 similar to the rack and pinion arrangement 15. As is illustrated, rack and pinion arrangement 89 is supported in the same manner as the previously described one denoted 15, and rack guide assembly 57 includes a roller 91 to support the rack 92. Actuation of rack and pinion arrangement 89 from the exterior of the chamber is provided by drive shaft arrangement 93 and an actuating knob (hidden from view).

The means for independently pivoting each of the sputter targets to a position between the target electrode and the substrate holder includes, like the mechanism provided for the same function with respect to the mask holders, an axially rotatable rod 96 which includes a lever and catch arrangement 97 for selective engagement with the slot in a tongue 98 on the desired one of the two sputter targets.

The manner in which the moving mechanism is actuated to position a selected one of the two sputter targets adjacent the target electrode is substantially the same as that in which the mechanism for the mask holders is actuated. However, the direction of the axial movement of the linear sleeve bearing 88 is generally reversed with respect to the direction of the sleeve bearing 48 since the sputter targets must be translated vertically downward into engagement with target electrode 18, rather than vertically upward as is the case with the engagement of the mask holders with the substrate holder.

From the above it will be seen that the apparatus of the instant invention provides a vacuum coating apparatus which is quite versatile and which does not require that the vacuum chamber be brought up to atmosphere before the interchanging of substrate masks or sputter targets at a work station. While the apparatus has been described with respect to a preferred embodiment, many variations can be made within the scope of the invention. It is therefore intended that the scope of the invention be limited only by the claims and equivalents thereof.

What is claimed is:

1. In a vacuum coating apparatus having a vacuum chamber which houses means for supporting a substrate to be coated by deposition of a coating material and means spaced from said substrate supporting means in the lineof-sight thereof for providing at said substrate an atmosphere of a coating material for said deposition, means for selectively positioning one of a plurality of members within said chamber at a preselected first location between said substrate supporting means and said means for providing a coating atmosphere and a preselected second location away from said preselected first location and not between said substrate supporting means and said coating atmosphere means, said selective positioning means comprising means within said chamber simultaneously supporting all of said plurality of members on an axis located within said chamber, means within said chamber for rotating each of said members independently about said axis to selectively position said members in said first and second locations, and means for moving each of said members along said axis to selectively position said members lengthwise of said axis.

2. The vacuum coating apparatus of claim 1 further including means for selectively moving said substrate supporting means to a location spaced from other structure of said apparatus to facilitate the positioning of a substrate on said substrate supporting means.

3. The vacuum coating apparatus of claim 1 wherein said preselected first location is against a substrate held by said substrate supporting means, and each, of said members is a holder for positioning a mask on said substrate to define the portions of said substrate on which said coating material is depositable.

4. The vacuum coating apparatus of claim 3 wherein means are provided for precisely aligning each of said mask holders with said substrate holder at said preselected first location.

5.The vacuum coating apparatus of claim 4 wherein said alignment means includes a socket on one of said substrate supporting means and said plurality of mask holders and a complementary pin on the other of said substrate supporting means and said plurality of mask holders.

6. The vacuum coating apparatus of claim 1 wherein said apparatus is a gaseous discharge sputter coating apparatus, said means for providing an atmosphere of a coating material is a sputter target electrode, each of said members is a sputter target of a desired coating material, and said preselected first location is at a position adjacent said target electrode at which a coating material will be sputtered from a target positioned thereat.

7. The vacuum coating apparatus of claim 1 wherein said means for moving each of said members along said axis moves said members simultaneously.

8. The vacuum coating apparatus according to claim 7 wherein said means for rotating each of said members about said axis rotates each of said members independently of rotation of the others of said members.

9. The vacuum coating apparatus of claim 8 wherein said means for simultaneously supporting said plurality of members on an axis includes a rod upon which said members are simultaneously slidable to provide said movement along said axis, and said means for rotating each of said members independently of the other members to said first location includes means for pivoting each of said members on said rod independently to said first location.

10. The vacuum coating apparatus of claim 9 wherein said means for independently pivoting each of said members on said rod includes a lever having a catch at one end thereof selectively engageable with a slot in each of said members for effecting said pivoting.

11. The vacuum coating apparatus of claim 9 in which said means for sliding said members together along said rod includes a rack and pinion drive.

12. Vacuum coating apparatus comprising a sputter target electrode, means for holding a substrate in line 8 with said target electrode, a support rod at one side of said target electrode, a first sleeve slideably mounted 1011 said rod, a plurality of mask holders mounted on isaid first sleeve for rotation about said first sleeve, means ifor individually rotating each of said mask holders about said first sleeve between a first rotational location substantially aligned with said substrate holder and a second rotational location substantially removed from said first location, means for sliding said first sleeve along said rod to selectively position each of said mask holders at a predetermined translational position such that when a mask holder is in said first rotational location and in said predetermined translational position said mask holder will'be closely adjacent said substrate holder, a second sleeve slideably mounted on said rod, a plurality of sputter targets mounted on said second sleeve for rotation about said second sleeve, means for individually rotating each of said s utter targets about said second sleeve between a first rotational position substantially aligned with said target electrode and a second rotational position substantially removed from said first position, means for sliding said second sleeve along said rod to selectively position each of said sputter targets at a predetermined translational location such that when a sputter target is in its first rotational position and in its predetermined translational location said sputter target will be closely adjacent said target electrode.

References Cited UNITED STATES PATENTS 3,480,535 11/1969 Bloom 204298 3,494,853 2/1970 Anderson et al. 204298 3,537,973 11/ 1970 Herte et al. 204298 3,206,322 9/1965 Morgan 204298 3,515,663 6/1970 Bodway 204298 3,494,852 2/1970 Doctoroif 204298 3,528,906 9/1970 Cash et al. 204-298 3,352,282 11/1967 Schweitzer 118-49 3,516,386 6/ 1970 Landwehr et al 118 -49 JOHN H. MACK, Primary Examiner S. S. KANTER, Assistant Examiner US. Cl. X.R. 

